Doors pose many dangers to users and to others who may come into close proximity to them. If a finger or other part of the body is caught in the gap of a closing door, the injury caused may vary from minor to serious. For hinged doors, such a gap can be created between a side of the door itself and the door jamb of a frame against which the door closes. When, say, a finger is caught in the gap at the handle side of a door, the injury may involve simple bruising if the door shuts relatively slowly or may involve more serious consequences if the door is slammed shut by a person or is driven by a strong draught with high velocity. However, the injury to a finger caught in the gap at the hinge side of the door may be even more severe. Such severe injuries, which occur relatively frequently in industrialized societies, and particularly among young children in homes, schools and child care centres, may sometimes require painful reconstructive surgery, or even amputation.
A prominent part of the cause of such accidents is the design of the door itself. As a hinged door closes, the gap between the door sides and the door frame narrows. At the handle side, the door closes much faster than it does at the hinge side, but the force of impact at the hinge side is much larger.
A typical door is about 820 mm wide and 35 mm thick, or is about 23 times as wide as it is thick. This means that when the handle side of the door moves through a distance of 23 mm, the hinge side moves only 1 mm, so that any force applied at the handle side is effectively multiplied by a factor of 23 at the hinge side. Even a slight breeze blowing a door shut could cause a serious crushing injury to a finger caught in the gap at the hinge side.
The designers of typical doors and door frames seem to have ignored the implications of their design to finger-pinch injuries at the hinge side, and have rather concentrated on designs that are standardized, efficient, visually appealing and economic to construct. In the main, such doors require a frame that has a doorstop located continuously along the under side of the head jamb of the frame, and have doorstops located continuously along each of the two opposed side jambs to form a continuous, three sided doorstop face against which the top and opposed side edges of the door will close.
For wooden doors and door frames, each doorstop is typically a 60 mm wide and 12 mm thick protrusion from the main body of the frame, and the position of the doorstop face within the frame will depend on whether the door is to open inwardly or outwardly. The door can be hung on either the left or right side of the frame, and once hung it can swing in only one direction. When shut, the top and opposed side edges of the door may come into or close to contact with the doorstop face. The function of the doorstop along the side jamb nearest to which the handle side of the door shuts is important in preventing the door from swinging all the way through the frame and ripping out the hinges that hold the door to the opposite side jamb. The function of the doorstop along that opposite, hinge side jamb, however, is less important to the operation of the hung door, being useful only for sound proofing and air tightness, and it is primarily a remnant of the desire for typical door frames to be of a standardized design to adapt to having a door hung on either the left or right side of the frame, and for such doors and door frames to be visually appealing by having a consistent appearance all the way around. Its presence poses a greater problem in terms of the risk of finger-pinch injury than any functional benefit it might have. Furthermore, the hinge side doorstop, because it extends into the door cavity from the door jamb against which the side face of the door closes, acts like a vice, whereby a finger placed against the hinge side door jamb will be pinched firstly at the point along the finger corresponding to where the inner edge of the door closes towards the outer edge of the doorstop, causing an immediate cutting effect and preventing the leading part of the finger being easily pulled out from against the hinge side door jamb.
While the majority of doors are of wooden construction, there are a large number of metal doors (especially in offices and industrial buildings), where the doorstop is a metal protrusion that is about 3 mm wide (as opposed to the 60 mm wide doorstop of wooden door frames), but as with wooden frames, it is also 12 mm thick. There are three such doorstops located respectively continuously along the under side of the head jamb and continuously along the two opposed side jambs of the metal door frame. Because of the smaller width and the metallic nature of the hinge side doorstop, the cutting and trapping effects on a finger placed against the hinge side door jamb will be more severe than that for wooden door frames, acting like a bolt cutter. These problems may be exacerbated if the door has an automatic (spring loaded) return system.
Far worse consequences may arise where fingers are trapped by metal security doors, which typically have knife-like inner edges instead of the squared corner, inner edges of other doors, and so have a guillotine-like action.
There have been various attempts in the prior art to address this problem, most of which have involved add-on or retrofitted devices to doors or frames of a typical design.
For instance, door hinge guards made of plastic and rubber have been used to cover both sides of the gap created as the door is opened and into which fingers may locate between the hinge side of the door and the frame. Another approach has been to prevent the door from closing unless an obstacle (which should be child-proof, like a panic bar) has been manually removed each time the door needs to be closed. Automatic door closers, which cause the door to pause just before it shuts, have also been used.
Although functionally effective, these devices require regular maintenance and replacement from the wear and tear they experience on a daily basis. Also, they can be easily damaged or removed, and have an aesthetically poor appearance. These factors have led to generally low market penetration for these devices.
It has been found by the present inventor that none of the prior art devices and methods for preventing finger-pinch injury at the hinge side of a door are reliable over the life of the door because they can, in certain circumstances, be separated from the door or fail functionally. In time, they will suffer the wear and tear of all movable attachments to a door.
The present inventor has found that a better approach to addressing this problem is to provide a door, frame and hinge assembly that does not create a gap between the hinge side of the door and the frame as the door is opened.
Some attempts have been made in the prior art to provide arrangements of door, frame and hinge assembly that utilize complimentary shapes of surfaces between the hinge side of the door and the frame side upon which the hinges are mounted. These have usually involved having a cavity defined at the hinged side of the door and a projecting part of the frame extending beyond the location of the hinge pivot point towards, and engaging within, the cavity.
U.S. Pat. No. 2,557,716 to Allee discloses an example of one such assembly. Although that assembly prevents a gap from being created between the hinge side of the door and the frame as the door is opened up to an angle of about 90 degrees, it requires complex, prefabricated hinge members to be fitted to, and extend along the full height of, adjacent sides of the door and frame. There may also be the problem that the slender, curved guard portion of the projecting part of the frame, which needs to have at least some part of it engaged within the cavity at the hinged side of the door to prevent finger-pinch injury, may be distorted in shape as a result of misuse or impact, and no longer serve its function.
Other attempts at utilizing complementary shaped surfaces between fixed and rotating sides of structures to prevent finger-pinch injury have also not been able to allow for such prevention up to 90 degrees, or just beyond that angle for corner located doors, but have a much shorter range of protected opening, usually no more than about 60 degrees depending on the relative structures of the projecting part and the cavity. Also, many such structures relate to sectioned panel-type garage doors running up and down tracks.
The present inventor has found that an even better approach to preventing finger-pinch injury is to provide a door, frame and hinge assembly that involves having a projecting part defined at the hinged side of the door and a cavity of the frame, the projecting part of the door extending beyond the location of the hinge pivot point towards, and locating within, the cavity. He has also found that the projecting part is best defined by a convexly curved surface, which preferably should be an integral part of the door, rather than being defined by a fitting to the hinged side of the door, although such a fitting is not excluded from the present inventor's approach to addressing this problem.